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OCR for page 68
6&
I:> S ~ .! T 'To r IDS
~ ~...,~ .,~._ ._ _
By
C. E. Truman and :~. (D'hagan
Gull' Research & T,evelopment (company
Pittsburgh, Pa.
ASTM SYL'-l POS IA ON INSULT IJG OIL
The most significant pl'-bl;cations appearir~g in 1947 Here the papers siren
at -the first too series of Symposia on Insulating Oil Sponsored by S,~con~ittee I~;
on Liquid insulation of ASTER Co~ni+>tee D-5 on ~Eiec-~rical Ins~:Lati~g 1~£ateria].sO The
first series Has held Ott tic 51~7 on October 169 1946 and the second series Has
also he] ~ at Atiantic C: ty off Jane ~ 79
191~70 A:J]~ o~ the papers toget':~.er with the
discussion :'corded at the meetings revere pul:l-'sried derring 1947 in the A'',Tl\E
Bulletin. ~ The s~r~osia were-' in gener21' concerned pith the rev. and o~-
-~ 4,
cussion of possible Bats of imp-c,v;-r~g t'r3e life of 1nsula~i.ng of] in =:i.~;`t,r~cai.
ar:~?aratus and also with the development; of lakoratc;`ry tests and meads of e-~a.luating
new oil, or oil for continued use for electr~.ca:L ins,xlat~.on pur,:;o.s~-!.s. :,r4~ W~l be
possible in this review to give only a genera;! idea. of the scone of the payers
and the discuss ons.
Tenting 7.~et}^ods
Interfacia1 Tension
__ .~
The interfacing tension of an of against, in.st~.7ea hater has shorn
promise of becoming a ~ralua'~le test to for the <~.'eteriora=~-ox~ of of] ::n service.
Proposals have also been made Chat the test be used as a criterion ~n ~ud.g~ng the
quality of an of' by fo:lo~ng the chute An the valve during 3abo~atorjr oxidation
of oil samples. Cereal ~ b and lF,!a].shk c both presentecL parers ~,uPpl:`r ng in+,er-
~acia] tension and other data on oils in service. C'n the basis of ~ stuffy of 124
transformers (ranging it size from 1000 to 3S'750 T.~.V.Ao) for a peridot of over
3 l/2 yearn Gerell tJ derived ~ relation 'cetreen the interracial -tension of an
oil and the probability that the Gil would be sludg~ngO It Has found that a31 oils
halting IoF.To values bellow 13 Tvere s1u6.gin{39 those t.av-~.ng 7.~.T. values c~to,.Te`.~.9
were rot sludging9 and the r)robakilit':r ~ L smudging increased as the I.F.T. ~ral~l<3 of
the oil decreased from I.9 to 7130 Walsh G also presented ~nterfacial tenon
power factors and neutralization number data on oils in service And a~t;te;~ptod to
arrive at ~ single Equality factors for evaluating the ser~r:~.edl~=e of an t~1 posed
on these data. In discussions of these papers, koth,':orse,h' and I*~ipp 1 d;
port; out that instances have been observed in which ~ ho interracial tension
did not(~e~Jessari]y mean that the oil was sludglngc Accordli.ng to FIorsch's obser-
vations g oils aged in opera transformers ~reci?:ntated sludge pith the of]
having an I.?,T. va:tue of about 1~4 Chile sa~n~.es of the SONG oil aged in sealed
transformers In the presence of r~it~ogon reached an I'~.To ~ra3Lue of about 15 with
no sludge Chorines.
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Representative terms from entire chapter:
atlantic cited
69
Steam Ems Number
Bal~er(1 a) discussed both the limitations of the present steam emulsion
+,=~st (~.~T.M. DJ57-96) and its ~os~!ib3!e '~tiliLv when the behavior of the oil
~`,ater emulsion formed' In the test; is carefully observed. Too examples were cited
.e'~e cont;amirLati.on of a transformer of: witI; bush~rlg cornpo~s caused high poser
factors ant! high steam e~n,:lsion test vaguest but the cox~tamir~at~cn had no effect
on the rleui;ra~;izatior1 number or or d.ic`~t,ric strengths A third example was cited
ill -ibid c.ontan1'y~aticn; by silica from an ins~lat,ing C00!pO~] between the transom
former la~nin.~ations CRUSOE extremely high poser factor but had no effect on the
neuira~ization n~riber, steam emulsion :~umber or on d.iolectr~e strengths
Dielectric Sir., ~ Application of Statistical Analysis
_,, .._ s_~ - ~._~. _. ~ - _ , PA, _ _ ~ . __ .
Greer~.elcl(] e) reviewed the a~pl~.~cat,~on of stat:.stical an=Isrsis in
handling available data more e~f~ciont1.y. Reference Its made to Chew ASTL: "Manual on
]?reser~tation of Data'', ]9330 A considerable amount cf dielectric strength data had
beers accum~la+~ed- in an attempt to `~stabl~sh the desirability of using (a). ~ rela-
t~.-~ely small Cuter of brea:~do~n shots on a large number of cup fi3-lings, or (b) a
r~,l.~t~:T<~.~;large nurse- of b:~ea'`~do~ns on a limited number o:f fillings O based on
t,16? data oft Noakes ~ P;ydro-Elect~i c dower Commis-sior~, the statisti.ca1 analysis by
&lcenfield indicated that gre<-lte.r accu.rac~y is Attainable by using the latter, or
pi ;~-~rea-6own-per-cup9 methods
Power Factor
~ - . .. ~ _-,~
Extensive data were resented by Ba~sba7=gh(2 e) in a d~,sc-:ssion of the
significarlce of the poker factor of an insul<~.~ng oil prluc~pa1~ly Proms the stand-
point off the 3abo~:-atc~rv teds and an analysis or. bile ~nechanisms involv:?~. Data were
p.~esent~d to show the phenomenal fly high power factor obtained -~.ith an oil in the
~escr~ce of copper or lead arid a limited o~-Lantity of oxygen. Art oxidation ~nh~..bitor
. ~ . . .
Was shorten co cause the same sort or limited c>~:idati.on to take place even though the
oil was exposed. to u~.~mi~ed quantities of open. Balsb~u~ stated that in the
normal opera~i.ng range roost of
tile c3lectr~ca' loss in an issuing oil is of the
ionic t`~eO consequently, the power factor ,.~;11 vary inversely with the frequency
and directly with the -viscosity of the oil.
Maintenance Tests - Genera
~ Pol~nan( g) discussed tile general prob' ems of the maintenance engineer
in dete~ri.~ling the condition and serviceability cf electrical eoinipment using iYlSIl-
lat,i~l~ oils. Po~nr:an pointed out that a serviceable insul<~i~titlg oil must: (1) be a
sat;~s~actory dielectric, (2) te
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70
(persllmably the same one
oil in 5 K.V.A. transformers operated for one year
the conclusion of the tests the acid number of the conventional Oil Was u.5 as
compared With the Sited oil acid number of less than 0.1. In discussion of
this paper, Horsch pointed out that the big problem in connection with the use
of inhibitors is in testing. He referred.to comparative laboratory tests in which
one inhibited oil performed well in an oxygen absorption test but showed little
improvement-over ~ conventional oil in other laboratory tests. This inhibited oil
did pot Atom much improvement over the conventional oil in actual transformers.
Fordt l ~ cautioned that a successful test in one transformer with an inhibited
oil is not conclusive eVidence-'that inhibitors Will Work in transformers generally.
Tbc inhibited of] remained stable during the induction period of the antiox~dent as
compared with the rapid deterioration of the conventional oils during the laboratory
test, Limited data were seven which compared. the Derformance of an inhibited oil
v - .- and an uninhibited
at 90°C. oil temperature. At
conventional oil was 0.5 a.~
given which compared. the performance
as examined in the laboratory tests )
Some of the background and practical problems concerned with the :~pl~-
cation of o=dation inhibitors to insulating oils severe reviewed by Berberich c .
Among the reasons cited by.Berberich.for the general lack of application of inhib~-
tors to insulating oils is that the inhibited oils have not yet been justified
either from an economic or a perfor ~ ce standpoint. Although laboratory tests
have indicated that improved performance can be obtained by the use of inhibited
oils, the final evaluation must be carried out in transformers Which requires a
long time to carry out. .. - ~
GEPlERAI
.
. In addition to the papers presented at the AST~.Symposia (discussed
above~, other publications on this subject are reviewed briefly below. .
Fork on standard methods of test ~ ~ insulating liquids has been con-
tinued.by ASTM Committee D-9, Subcommittee IV ~ Further progress has been made
toward reorganization of method D-~17 to make.~t.eventually ~ reference method
giving only definitions and statements of significance. Cooperative tests Were
continued on methods of test for interfacial.tension, water in oil, sulfur corrosion
and also on the correlation of data obtained by D670-42T sludge tests and other
methods of test With performance in commercial transformers.
Hurwortht4) has presented evidence (covering inspection of 2000 units)
which indicate that sludge deposits found on transformer lids and oil-circuit
breaker parts above the oil level are caused by the action of electrical stress on
the oil vapor. This idea was checked in the laboratory by aging three glass .
beakers of of] at 55°C. in which steel electrodes under a stress of 15,000 vG1tS
first With both electrodes com
one above the oil, and the third
.. .
with both electrodes above the oil. At the end of six months9 the acidities of the
OiiS ~6 increased in the order listed above, that is' the sample aged with the
electrodes completely out of the oil had the highest acidity. lI~orth presented
other evidence from service that electrical Stresses in the oil orator space had
caused abnormal deterioration and corrosion.
This idea was checked
at 55°C. in Which steel electrodes
A.C. were placed in the following positions. the
nietely immersed' the second with one immersed and c
71
Results from laboratory tests to determine the effect of various metals
and insulating varnishes on acidity and sludge formations in transformer oil were
given be (~,legg ( 5 J .
TJnsworth(6) has reviewed the criticisms of the British Standard S~eclfi-
cation for transformer oil (BASE 148-1533)0 He stated that it is generally regarded
as fai].ang to provide a satisfactory test for oil cete.rioral;ion, particularly from
the star~oint of acidity development resulting from oxidation. Unsworth suggested
that e:Lectrical properties should also be considered moo e critically then the oil is
wised in other electrical apparatus such as oil~immersed s~vil;chgear and capacitors.
A general discussion of transform;~0il characteristics and development
of acidity in service Alas rublished by Harrap ,.
and by Tyrlan ~ 9 ~ O
Reconditioning transformer oil in the puniest of n~blin.ntion=. bar Hall (g)
Improved insulating oils were claimed in the following U. S. Patents a
Stratford, et s1(1°) - A phenol-extracted petroleum distillate
having a ratio of paraffin to naphther~ic constituents of at least 3 to ~ is
treated at execrated temperatures With 4-7% activated c].ar in the presence of
0~75-~.25% t~yArated lime to obtain ~ stabilized oil having improved.oxidation
resistances
Soday(ll) - An insulating oil composed of a mixture of high boiling
aromatic oils is obtained by the vapor-phase pyrolysis of petroleum oils.
Flynn(l2) - C.05-0~% naphthoq~inone is added to oil to stabilize
it against deterioration brought about by presence of r~icro-organisms.
The classification and propertied g; lusulating oil requirements for
electrical equipment were reeked by Qua~rle 1
Synthetic Insu]..atin~ Liquids
The increasingly important role of thy chemist in solving insulation
problems Has emctias~zed in an article by Clark(l4 . The adoption of pentachloro-
di~henyl in capacitor manufacture r?as cited by Clark as representing an instance in
Which 3, more expensive synthetic product rep]..aced, on a large sca3~9 cheap, natu-.
rally occurring mineral oilO other elect~ic~1 insulation requ~.rements and the
deveJop~..ent and application of synthetic compounds offered as mat`>ri=~.s to meet
these requirements are discussed by Clarke
t.4clean(~) presented data on the electrical properties of paper capaci-
tors impregnated With chlorinated di.phenyl. The effect of controlled oxidation is
sh..o~.~n to be beneficial and lasting ~ln.en ant~:a.quinane is present in the liquid
impregnant.
72 ~
New synthetic c ompos~.tio.n or irn.proved J iqu id .iri~ulc tion Rat ~.ri.~1 s are
the sub jects of rear nt patients as i.rldi cited tri;ef7''r OCIO1~-DWO
.Hamil-tcntl6' .
. .
. . , ·, , ' .
. . .
MlxfJure t of Minerals. cad l, sol id pol.yln~?ri..~ed
ethylene, arid poly~sc,Lutylone.
. . . . .
E. I. DuPont de Nemo~lrs & Coln~hr~-7! 7)
;Cl3.rk ( )
Pol.yrneric clLe ?in-'c ^*ompour~ds Prepared in
Presence of An a~ni.ne oxide ca+.,a~ys,'.
. , .
Fixtures of chlorinated hydrocarbons
cc,n+~=n,~ crystal ~nh:Lb~to.rs such as
mineral oily.
- CIark(~9~'
. . .
Combi~3tiOrls Gi arornat-'c sun s and
ch]:or~nated hydroca~.bor~sO.
Clark(20) published an account of the develQp3nent of capaci.'.;or~ based
on the use of serni~corlducti}:lg li.qui~ds ~:ith,-cel-~.ulo~e ~,sul~tictl.
~. ,
,,, , ~, r
-
'73
LIB~TO~RAP~
_. ~-
lo ~yin~>t~siUm con Ins~llat.i~l~ Oils Atlantic Cited, h. ~., October 16, 1.9460
'?Stear.-~nu:Lsion Number as an index of Transformer Oil Serviceability,'
M. D. Baker, ASTM Ru:l ~ el;i rat, No. ~469 pa 90-2 (1947)
be 'ache ~xl~erfa.cial Tension Chest and it,= Significance ~ n Appraising P;-rforrn~"
once of an Insu:lat,i^~g 0~1'~ - G. ~0 (beret l., And Bulletin, No. 146,
p. 92 - 5 <] 947)
c.
L ~
e
to
L ~
"App~ ic~tior~ of tI~e ; nte;~ac:La1 '`.~ensl.~ Te st ~ n OTradin~ 0;1 i.n T: ansfo, me:: s
R~la'~ive to S=rvice~nb~lit~rl' - ~ a Fo Wa~h, AS~4 Bul~ et~.n' tJ°. 146,
p. 95 - g (~-947)
~is2u~,~ion Gf O-'coNre papers 9 AS~` Pu7.1e+J~ n9 No. 146, p. 99 - lQO (3 947)
ttRef~ esher on Statis~ti c al. Anal~rsis Appli.ed to Tr.rc A`STId1 Oi]. D~ electiric
Strength Tcast Procedur=3lt - Eo W. :~-reenfi~j3d, ASIIt'l1 P)ul~eti.n, Nco 1499
pO S9-54 (1947)
. . .
?o S3r~pcsiulm cn Insula+ing ~,.) 9 Atl antic cit~y9 M. J. 9 June 17, 1947 - Second Seriec
aO tt~..dv?~nts.~es of an Inl~i.~te¢~i T,&,nsformer O~l" - ~0 E. Reamer and
R. G. ~ arsen, AS~,lI Sul'ct~n9 7IcO ]49, p. 56-~ (1947)
b. :5iscussion cf above ~pO~9 AS~: ~,~2~t~l, t;rOO 149, fjO 64-3 .(1947)
itOxid.~c~n ~' nhibi.t;ors :} ~ Eiec ur:~` a.1 Insu.latirig ^~] s'' ~ I~co J . T3erberich
ASTM Bu~le+~ir, lTo. 1499 ~?. k5-73 (194.7)
d. Discu~s,on of above ~apor9 ASTL!' Pul:l.ctir$ -~ToO 149, p0 73-4.
"Po.~r Factor of -`nsl~lat;.n~, °i2.sg I~,s Signif~cance- and lvie~tods of ~i'esting
~Stc;`b1.ii~ytt - T, CO 3~],sb~ugh9 .5STM .3l~=et`ng i100 1499 ?. 75-82 (1947)
fO Di sC-ilss or1 of abo;~e ~aper - ASTM fuLlet n9 Fo. 1499 pO 82-4 (19~7)
E. "SCrV~.CO~bi'itTr T¢S!G~ on 1ransfo`7!.er 011 Fro~n the lTie~point of -Gbe ~5ainte-
nance Engin~er' - Fr~nk ., . Po~ina`~, AS~.~1 Bu' let-in ~ o. 1495 ~. 84-~S (194.7)
ho Discussior~ of atove paper - AS~`E Pu`~.et~n r`.~TOO 149 g pO 88-9 (1947)
3. ~A._S O T O 'li~. ~Proo ~edincs ~ /~7' pp 0 335-8 {L9b7)
XUr`~OrtIlg ]-~. ~ ~= ~g ~gi`.9 pp. 608-: (] 947
50 ~1egg, J. A., El~c. R'
(Lc,ndcn ) ~ 40 9 pp O 947-9 ( 3 947,
6 ~U, s~orth, A. 9 ~)CC. R. (.~ondon' ~'40, cp. 83 ~4 (~947)
74
7. i-Iarrap, G. +\;r. t ~c, R. (J.!or~dc~n ~1~9 pp. 939-91 (1946)
~0
Hal]., A. C.' .r~;o~a~r and ~o_-s Error. i-29 #487' 18 (1947)
9. Tynan9 H. A. ~ Ele_ri~al W-G_ id, i;. 84, (:1.947>
lOo Stratford et al, A.~signo' to Starboard. O.l .F)~r:~lopme.~t Company9 U. So Pa~r-~r~t,
2'420 Silos May 6, 1947
llo sod-£;T9 F.S Assignor to The TJnntr3d Cons Tm~:'rov:;~;nent Gon~par~.r, UO S. Patent
2,423~413 July is 194?
12. Flynn9 E. S. 9 Assignor to Anaconda dire and Cable Company' U. S. Patent
2 9 425 9 751 August 19 9 1947
30 Quayle9 Jo Cog ns+itute~of~Pe+,roleu.-n Pev~,eT. ~(London) 19 ppc 13'3-7 44 (i°,47'
18. Clark, F. A. 5, Assignor to Gr;r~eral Electrical Company, TJ. S ~Patent, 2 9413, 17C
De00EbCr 249 1946
14. Clark, F. [¢. g C fem. `ano4_En=. hers, 25, A. 29rr6-789 (3947)
15 McLean, DO A bird and F=o Ch(3ma ~ 39, ppo 3457-~71 ~ (19L7)
o · 9 ~ ° ~
16. Hamilton, G. Mo, Assignor: to Caller~de~r~s Cable c~nd '^orlstr'~lctio~ '~3. T'tdog
IJo S. Patent 2~.49300 J£lr~uary 14, t947
E. :E, DuPont d~ Nemcurs !- Co~.pan~r, British Patent 5259396 February 6, 1947
190 Clarke 1?. D'qe7 Assignor to General Electric Company-, TJ. S. Patent 2~.;L10~714
No:Tem'~er 5, 3 946
20. Clark' F. M. g ~ene.ral_Llectric Rev. 50g #29 9~ L7 (1947)
, · .
.. ..
